1. Field of Invention
The present invention relates to medical equipment used for examining swallowing, and, more particularly, to the use of this equipment to produce a manofluorograph and a monofluorogram to aid in the diagnosis and treatment of disorders in the digestive tract. The equipment combines pressure sensor measurements with contemporaneous videofluoroscopy of a patient swallowing a radiopaque bolus past the sensors on a catheter.
2. Description of the Related Art
Analyzing the physiology of swallowing has long been regarded as a challenge. So many events occur in such a rapid sequence that the prior art has not been able to precisely characterize source of pressure and quantify the amount of pressure applied to the bolus during swallowing.
Mere fluoroscopic analysis of a patient swallowing barium provides only superficial insights into the nature of swallowing and many problems associated therewith. Videofluoroscopy has provided more detail than fluoroscopic analysis, but equipment for time-framing is not built into the video recorders ordinarily used by radiology departments.
Manometry is rarely used to analyze events above the pharyngoesophageal (PE) segment. When manometry is used, it has been difficult to assign pressures to specific pharyngeal structures. E. M. Sokol, P. Heitman, B. S. Wolf, et al., Simultaneous Cino-Radiographic and Manometric Study of the Pharynx, Hypopharynx, and Cervical Esophagus, Gastroenterology, 960-974 (1966). Also, the pharynx has been difficult to evaluate through manometry because of rapid, precipitous pressure changes and the proximity of the airway. W. J. Dodds, W. J. Hogan, S. B. Lydon, et al., Quantitation of Pharyngeal Motor Function in Normal Human Subjects, J. Appl. Physiol. 692-696 (1975).
Most manometric measuring devices that have been used in the pharynx were developed for measuring the pressures of the esophagus. These instruments are inadequate for the dynamics of pharyngeal manometry because the pharynx and the esophagus are functionally different. The pharynx generates pressures of 200 to 400 mm Hg at rates of up to 4,000 mm Hg per second. Esophageal peristalsis is a much milder event. Esophageal pressures reach only 80 to 140 mm Hg at rates of 160 to 400 mm Hg per second. Pharyngeal waves travel at 9 to 25 cm per second, compared with 4 cm per second in the esophagus. Id. A flat frequency response rate of up to 5 Hz is required for manometry for esophageal pressure. J. Orlowski, W. J. Dodds, J. H. Linhan, et al., Requirements for Accurate Manometer Recording of Pharyngeal and Esophageal Peristaltic Pressure Waves, 17 Invest. Radiol. 567-572 (1982). The measurement of pharyngeal pressures requires a frequency response rate of up to 48 Hz. Investigators using infusion catheters to measure pharyngeal deglutition have reported questionably low pressure peaks of less than 100 mm Hg, suggesting inadequate manometer frequency response rates.
Previous attempts to examine swallowing by combining video fluoroscopy and manometry have involved water manometry: F. M. S. McConnel, M. S. Mendelsohn, J. A. Logemann, Examination of Swallowing After Total Laryngectomy Using Manofluorography, 8 Head Neck Surg. J. 3-12 (1986); F. M. S. McConnel, M. S. Mendelsohn, J. A. Logemann, Manofluorography of Deglutition After Supraglottic Laryngectomy, 9 Head Neck Surg. J. 142-150 (1986); and M. S. Mendelsohn, F. M. S. McConnel, Function of the Pharyno-Esophageal Segment, 97 Laryngoscope 483-489 (1987). Unlike solid state sensors, water manometric sensors have a time lag of about 0.1 second from the time of pressure initiation to its display. Due to this delay, the use of water manometers provides data that lags the videofluoroscopy pictures. Thus, combining of such data with simultaneously produced videofluoroscopy does not accurately portray swallowing.
A solid-state strain gauge can accurately measure pharyngeal pressure transients without the time lag of water sensors. These transducers have more appropriate frequency response rates and give high-fidelity recording of the precipitous pressure gradients. The newer gauges are more temperature-stable and less fragile than the previous semiconductor devices. The gauges can also be oriented to "look" in one direction.
Another of the difficulties in the measurement of pharyngeal pressure is the existence of radial pressure differences. Radial manometry at the cricopharyngeal area reveals a marked asymmetry, with pressures higher in the anteroposterior dimension than in the lateral dimension. R. W. Welch, K. Luckmann, P. M. Ricks, et al., Manometry of the Normal Upper Esophageal Sphineter and its Alterations in Laryngectomy, 63 J. Clin. Invest. 1036-1041 (1979).
Catheter movement has been thought to cause erroneous PE segment pressure measurements. PE segment elevation is 1.2 cm greater than the catheter elevation during normal deglutition. A. Isberg, M. E. Nilsson, H. Schiratzki, Movement of the Upper Esophageal Sphincter and a Manometric Device During Deglutition, 26 Act Radiol. [DIAGN] (Stockh) 381-388 (1985) and A. Isberg, M. E. Nilsson, H. Schiratzki, The Upper Esophageal/Sphincter During Normal Deglutition, 26 Act Radiol. [DIAGN] (Stockh) 563-568 (1985). See also W. J. Dodds, P. J. Kahalas, J. Dowd, and W. J. Hogan, Considerations about Pharyngeal Manometry, 1 J. Dysphagia 209-214 (1987). The catheter sensor can move out of the PE segment high-pressure zone. During a swallow, the rapid movement of the tongue, palate, larynx and pharyngeal walls occurs such that the level of each structure can change 1-3 cm. A catheter may also move this distance at the tongue or palate. Thus, it has been difficult to associate specific physiological events in the pharynx with pressure measurements and to determine the role that pressure changes play in bolus passage.
Among the studies which have combined fluoroscopy and manometry are the above referenced Isberg articles as well as Sokol, Id. Sokol and colleagues defined three different types of positive pharyngeal pressure waves: the E, T, and P waves. The E wave occurs in association with laryngopharyngeal elevation. The T wave onset coincides with backward movement of the tongue base. The third and largest positive wave was termed the P wave because it coincides with the peristaltic stripping wave visible by X-ray. In the classic description, the peristaltic wave starts at Passavant's ridge and travels down the pharynx.
In sum, the prior art has not precisely related measured pressures to the passage of the bolus to allow quantitative analysis of swallowing. Thus, diagnosis and treatment of swallowing disorders has been limited.